1. Field of the Invention
The present invention relates to an eyeglass frame, and more particularly to an improved temple joint structure.
2. Description of Related Art
As shown in FIG. 9, a conventional eyeglasses frame has two temples "b" hinged to the opposite sides of a front so as to permit the opposite temples "b" to fold on the front. One joint piece "a" is soldered to either side of the front, and one and the other hinge pieces "c" are soldered to the inside surface of the joint piece "a" and the inside surface of each temple "b" respectively, thereby permitting each temple to rotate with respect to the stationary joint piece. The temples, however, cannot fold on the front stable for a long period; the hinge screws are liable to be loosened, or the associated parts rubbing with each other are liable to wear until the temples have lost correct postures relative to the front, causing displacement of the eyeglasses from the correct position when wearing the eyeglasses on the face.
Hinges are so small that they cannot be made with ease. The hinges do not allow the temple to open wider than 180 degrees relative to the joint piece (see the solid line in FIG. 9). This opening degree is adequate enough to wear the eyeglasses on one's face, and the flexibility of each temple permits the yieldingly bending of the temples enough to enable the eyeglasses to fit on one's face.
Eyeglasses usually fit on one's face for the while after being bought and used. The temples can restore their original postures relative to the front of the frame unless they are deformed perpetually, but the hinges are liable to be loose, causing the rattling of the temples. Also disadvantageously, the conventional temple joint cannot absorb a shock when applied to the frame of the eyeglasses, thus allowing the eyeglasses to fall from one's face, causing the breaking of lenses or deforming of the frame of the eyeglasses.
In an attempt to solve such problems there have been proposed temple joints which permit each temple to open wide more than 180 degrees relative to the joint piece of each end of the front. One example of such temple joint is shown in FIG. 10, and is called "spring hinges". As shown, a stationary hinge piece "d" is soldered to the joint piece "a", allowing a slidable hinge piece "e" to slide a given constant distance to permit the temple "b" to open outward beyond 180 degree position as shown in broken lines.
The temple "b" has a guide piece "f" fixed on its inner surface to guide the slidable hinge piece "e". The slidable hinge piece "e" has a coiled spring inside (not shown), and it is yieldingly compressed when the temple "b" is opened outward beyond 180 degree position, thus applying a returning resilient force to the temple. As may be perceived, the hinge structure having a coiled spring contained in its slidable hinge piece is very complicated, and accordingly an increased number of manufacturing steps are required, and it is expensive. Still disadvantageously, it is easy to malfunction, and is difficult to be fixed once something has been wrong with it.
Spring hinges are likely to be loose as is the case with ordinary hinges, and therefore, the stable attachment of the temples to the front is not assured. A temple hinge structure disclosed in Japanese Utility Model 2-16330(B) is simple in structure, compared with other conventional spring hinges. Each temple has a pin to be caught by a circular-curved piece, which is fixed to the joint piece on either side of the frame. The engagement between the pin and the circular-curved catch is prevented from loosing by an associated spring. The pin of the temple, however, cannot be engaged with the circular-curved catch of the joint piece with ease. What is worse is: the circular-curved catch of the joint piece is fragile; even if the circular-curved catch is made of a hardened metal, it is annealed when heated by soldering to the joint piece. When the temples are opened outward, the tip of the circular-curved catch is often caught by the circular recess of the sheath, thus preventing the smooth opening of the temple.